def grade_wrong():
    score = float(input())
    if score >= 60:
        grade = "D"
    elif score >= 70:
        grade = "C"
    elif score >= 80:
        grade = "B"
    elif score >= 90:
        grade = "A"
    print("输入成绩属于级别{}".format(grade))


def grade_1():
    score = float(input())
    if score >= 90:
        grade = "A"
    elif score >= 80:
        grade = "B"
    elif score >= 70:
        grade = "C"
    elif score >= 60:
        grade = "D"
    print("输入成绩属于级别{}".format(grade))


def grade_2():
    score = float(input())
    if score >= 90:
        grade = "A"
    elif score >= 80:
        grade = "B"
    elif score >= 70:
        grade = "C"
    elif score >= 60:
        grade = "D"
    else:
        grade = "E"
    print("输入成绩属于级别{}".format(grade))


def grade_3():
    score = float(input())
    if score >= 60 and score < 70:
        grade = "D"
    elif score >= 70 and score < 80:
        grade = "B"
    elif score >= 80 and score < 90:
        grade = "C"
    elif score >= 90 and score <= 100:
        grade = "A"
    else:
        grade = "E"
    print("输入成绩属于级别{}".format(grade))


if __name__ == '__main__':
    # grade_wrong()
    # grade_1()
    # grade_2()
    grade_3()
